An image erasing apparatus according to a related art includes a large metal detection apparatus to detect staples or the like attached to a recording medium. Therefore, there is a problem in that the size and cost of the image erasing apparatus is increased. In addition, in order to solve this problem, a method of optically detecting staples instead of performing metal detection is known. However, the optical detecting method has a problem in that an image formed on a recording medium and a staple cannot be distinguished from one another.